Dr. David D. Ho is a summa cum laude graduate of California Institute of Technology, and of Harvard Medical School. He completed his medical internship and residency at Cedars-Sinai Medical Center, UCLA Medical School. Thereafter, he served as chief resident before becoming an infectious diseases fellow at Massachusetts General Hospital and Harvard Medical School. He has been working in the laboratory of Dr. Martin S. Hirsch for 15 months. In 1986, Dr. Ho will become a faculty member of MGH and Harvard. The major objective of Dr. Ho's proposed investigation is to define the oncogenic processes leading to Kaposi's sarcoma (KS), a vascular tumor now occurring at an alarming rate as a manifestation of the acquired immune deficiency syndrome (AIDS). Both cytomegalovirus (CMV) and human T-lymphotropic virus-III (HTLV-III) have been linked to this neoplasm. Therefore, the in vitro transforming capabilities of these viruses on endothelial cells, the target cell of KS, will be examined. Transformed endothelial cells will be studied for anchorage independent growth on semisolid medium and for tumorigenicity in nude mice. The transformants will also be cultured for viruses, and assayed for specific viral markers. In addition, KS tissue will first be examined for CMV and HTLV-III, and their respective viral antigens and DNA sequences. Furthermore, DNA extracted from KS tissues or cell lines will be used to transfect NIH 3T3 cells by the calcium phosphate precipitation technique. The transfectants will also be tested for anchorage independent growth and tumorigenicity, and analyzed by DNA-DNA hybridization studies for CMV and HTLV-III nuclei acids, human repetitive sequences, and an array of oncogenes. Preliminary studies conducted by Dr. Ho are encouraging, and they suggest (1) endothelial cells can be infected with both CMV and human T-lymphotropic virus and (2) KS DNA can induce transformation of NIH 3T3 cells. Dr. Hirsch's laboratory consists of 3 faculty members (in addition to Dr. Ho), 4 fellows, 5 technicians, and one visiting scientist. This group is part of the Infectious Disease Unit, comprised of 15 faculty members. There is close professional contact between Dr. Ho and others, particularly Dr. Hirsch.